George Zimmerman, the Florida man accused of second degree murder for the death of Trayvon Martin, didn't take the stand, but his voice filled the courtroom today as jurors listened to him explain several times how he came to shoot the teenager.

"He was on top of my…I shot him, and I didn't think I hit him because he sat up and said, 'oh gosh you me, you got it, you got me, you got it," Zimmerman said to lead investigator Chris Serino during a video re-enactment that was shown to the six women on the jury for the first time.

Zimmerman, 29, is charged with second degree murder. He maintains that he shot Martin, 17, in self defense.

Serino, who unsuccessfully recommended that manslaughter charges be filed against Zimmerman soon after the shooting, said Zimmerman appeared to be relieved when told him the shooting had been videotaped.

"Thank God," Zimmerman replied.

Serino said based on his response he thought Zimmerman was either a pathological liar or telling the truth, but concluded that Zimmerman truly wished the incident was videotaped. The shooting, however, really wasn't taped.

The officer responded, "If what you're telling me is true, I don't think that what God meant was that you couldn't save your own life."

In his initial report in which he recommended manslaughter charges, Serino wrote that Martin's death could have been avoided if Zimmerman, a former neighborhood watch captain, had not left his car after calling police to report a suspicious person on Feb. 26, 2012.

In his interview with Zimmerman, Serino asked, "Did you pursue this kid? Did you want to catch him?"

"No" Zimmerman responded.

Zimmerman claims that Martin knocked him down and banged his head on the sidewalk.

In their interrogations Serino and Singleton appeared skeptical of Zimmerman's account that Martin covered his mouth and smothered him as he screamed for help, telling him that if someone puts their hand on a screaming person's mouth "It's going to stop."

In a Feb. 29, 2012 interrogation when Zimmerman clarified that he called Martin a "f**king punk" Serino shot back, no he wasn't.

In her questioning of Zimmerman, Singleton asked, "Do you think he was scared?.... When people are following you and trying to talk to you…you never told him who you were."

"I didn't have the opportunity," responded Zimmerman.

"But you could have told him," Singleton shot back.

As the second week of testimony began today, the prosecution appeared to be moving away from neighbor witness testimony and are now focusing on forensics and the initial investigation in the early days of the case as they attempt to answer the question about who started the fatal altercation.

Prosecutors first called Singleton to the stand and played Zimmerman's first recorded statements made soon after he waived his Miranda rights and spoke without an attorney present.

"He jumped out from the bushes and said what the f**k is your problem," Zimmerman said to Singleton. "I said I don't have a problem and then he punched me in the nose."

"As soon as he punched me I fell backwards. He was whaling on my head and I started yelling help," said Zimmerman. "He grabbed my head and started hitting me into the sidewalk. I slid into the grass to get out from under him. I was still yelling out for help."

Zimmerman said Martin told him, "You are going to die tonight" and kept banging his head into the sidewalk, and that he shot and killed the teen soon after.